Telegraph relay



V. J. TERRY TELEGRAPH RELAY Dec. 25, 1951 2 samrwsm'w 1 Filed Feb. 12,1948 Inventor 78M 7 W Attorney Dec. 25, 1951 TERRY 2,579,523

I TELEGRAPH RELAY Filed Feb. 12. 71948 2 ampsrmm 2 INJUL fi Tia/V F/GB.

Invenlor W Td/M, 7

A tlorney Patented Dec. 25, 1951 2,579,523 TELEGRAPH RELAY Victor JohnTerry, London, England, assignor to International Standard ElectricCorporation, New York, N. Y., a corporation of Delaware ApplicationFebruary 12, 1948, Serial No. 7,911 In Great Britain January 24, 1947Section 1, Public Law 690, August 8, 1946 Patent expires January 24,1967 4 Claims. 1

This invention relates to electro-magnetic telegraph relays of the typein which the tongue of the relay carries two contacts which move betweentwo fixed contacts according to the movements of the armature of therelay and is particularly concerned with means for mounting thecontacts.

The objects of the invention are t provide a relay in which chatteringof the contacts against one another is reduced or eliminated and inwhich the change-over time can be made vanishingly small.

In the normal type of telegraph relay an armature of magnetised materialis pivoted or held at one end in such a way that it can move between thetwo poles of an electro-magnet under the influence of signalling currentpassed through the windings of the electro-magnet, commonly known as therelay windings. From the free end of the armature there is extended inline with the armature a strip (or strips) of metal known as the tongueand near the free end of the tongue two contacts are mounted, one oneach side of the tongue and opposite one another, the contacts being sopositioned that they lie between two fixed contacts carried on supportsattached to the main frame of the relay. When the armature moves underthe influence of signalling currents in the relay windings the contactson the tongue are pressed against one or other of the fixed contacts.

The contacts which move when the armature moves will be referred to asthe moving contacts while the contacts which are supported on the frameof the relay will be referred to as the operating fixed contacts. It isnormal in using such relays to connect the positive pole of a signallingbattery to one fixed contact and the ne ative pole of the same batteryto the other fixed contact.

The tongue of the relay is connected to the line or apparatus into whichthe signals are to be relayed, the circuit being completed by aconnection to the midpoint of the signalling battery. The purpose of therelay is to transmit square shaped signals corresponding to thesignalling currents passing through the relay windings and with asnearly as possible the same time spacing as the original signals.

When the tongue of a relay such as is described above is thrown over toone side by a signalling impulse the moving contact tends to bounce offthe fixed contact and a condition known a chattering is set up so thatthe current delivered by the relay is not steady as is desired but isinter- 2 mittent at least over the first part of each relayed signal.

Many devices have been introduced t overcome this chatter of which thegeneral principle is that either the fixed contacts or the movingcontacts or both, are so mounted that they can yield slightly under thepressure exerted by the armature. Yielding contacts of this type areusually mounted on springs.

Although mounting the contacts on springs efiects an improvement somechatter still occurs at the moment of impact between the moving andfixed contacts and it ha generally been found desirable to incorporatesome method of dissipating in the form of heat the kinetic energyreleased at the moment of impact. This can be accomplished by arrangingfor the impact to be accompanied by friction between two membersassociated with the contacts.

It is always desirable that the response of the relay to changes ofdirection of the signalling current in the winding shall be, as nearlyas possible, instantaneous. When the contacts of the relay are mountedon springs which yield under pressure, it is evident that when thecurrent in the relay windings is reversed, there will be some movementof the armature during which the springs will keep the contacts togetherwhen they should ideally be open.

The electrical circuit through the other fixed contact cannot beestablished until the tongue has at least reached the neutral portion sothat the outgoing signal from the relay will be slightly later in timethan the received signal passed through the windings. This would notusually be of importance in itself provided an equal time delay occurredat each reversal. As however the received signalling currents throughthe windings do not build up to their maximum value instantaneously, thesprings will be more deflected in the case of a signal of long durationthan one of short duration and therefore the change-over time delayswill vary, with the result that distortion will be introduced and theoutgoing signals will not be faithful replicas of the original signals.

By using the construction now proposed, the advantages of resilientcontacts can be obtained,

in conjunction with the frictional dissipation of the kinetic energyreleased at the moment of impact while the changeover time can bereduced at will, till the time of travel between contacts is zero, and,in fact, it can be reduced until the make-before-break facility isobtained, that is to say, that one of the moving contacts will be incontact with its cooperating fixed contact toa wards which the relaytongue is moving before the other moving contact has become separatedfrom its cooperating fixed contact.

The invention provides an electro-magnetic relay comprising an armatureon which are mounted two contacts, said contacts being so positionedthat they co-operate with two other contacts mounted on the staticframe-work of the relay when the armature moves under the influence ofsignalling currents in the relay windings, characterised in this, thatat least one pair of similarly acting contacts is mounted on a rigidsupport in such manner, that the two contacts of said pair are held aconstant distance apart, said rigid support being carried in a resilientmounting so that any movement of one contact of said pair is accompaniedby an equivalent movement of the other contact of said pair.

Various mechanical constructions can be devised for embodying theprinciples of the invention but only three embodiments, will, bedescribed. The magnets, windings and armature. of the, relay are notillustrated as they do not form any. part of the invention and may be ofany suitable construction.

The invention. will be understood from the following description takenin conjunction with the accompanying drawings in which:

Fig. 1 shows resiliently mounted. contacts according. to oneembodimentof the invention.

Fig. 2 shows an alternative embodiment of the invention, and

, Fig. 3 shows yet another embodiment of the invention.

In Fig. 1 there is shown a member l carrying two contacts 2, amounted ona cylindrical extension l of a relay tongue 5. The tongue 5 is anextension of the free end of the magnetic armature of the relay, thetongue and armature being of any suitable construction. Under theinfluence of signalling currents in the relay windings the armature (notshown) and with it the tongue 5 moves to the right or left (as shown inthe figure) as indicated by the arrows 6. The

member l carrying the contacts 2, 3 will be rea:

ferred to hereinafter as a spider. A hollow cylindrical huh I is anintegral part of the spider. The cylindrical extension '5 of the relaytongue 5 has mounted on it a resilient bushii which bush may be made ofany suitable resilient material such. as, for example, natural orsynthetic rubber. The inner surface of the resilient bush is firmlyattached to the cylindrical extension l so that it is not free to rotatethereabout and the inner surface of the hollow cylindrical hub l of thespider l isfirmly attached to the outer surface of the resilient bush 8,the two arms'ofthe spider, carrying the contacts 2-, 3 being arranged sothat the. line through the two arms is perpendicular to the plane ofmovement of the armature indicated by arrows 6.

The two contacts 2, 3project in opposite senses from the arms of thespider and constitute the moving contacts of the relay, co-operatingwith two fixed contacts 9, l9 adjustably mounted on the fixed frameworkof the relay. An electrical connection to the moving contacts isprovided by-means of a flexible connection H.

From the, above described construction, it follows that the spider willbe given a small amount of rotational movement around the relay tonguewhen pressure is applied to the arms of the spider, owing. to theelastic deformation of the resilient bush, and that the spider willreturn.

to its normal position when the pressure is released.

In. an actual construction, contact pieces of the usual type are mountedon the armsof the spider, one near the end of each arm, and sopositioned that they project from the arms along lines which areparallel to the direction of travel of the tongue of the relay.

To understand the working of the relay, consider firstly that the tongueof the relay is in a neutral position with no current flowing throughthe relay windings. The fixed contacts may be adjusted so that there areonly very small gaps betveen them and the moving contacts. If, now, asignalling current is passed through the relay winding, the armature andtongue will travel to one side and one of the moving contacts will pressagainst its associated fixed contact and the spider will be rotatedaround the tongue through some small angle. The resilient bush yieldssufiiciently to minimise the tendency. of the contacts tochattenandcwing to the nature of'the material of the bush, a certainamount of damping is introduced by the natural internal friction of thematerial.

A further and perhaps more important advantage of this arrangement must,however, be noticed. As soon as one moving contact is, pressed" againstits cooperating fixed contact, the spider commences to rotate. Thiscauses the other moving contact to be given a movement away from itscooperating fixed contact in addition to the, movement in the samedirection due to the normal travel of the relay tongue. In other wordsthe contacts open twice as fast as they would for the same speed oftravel of the tongue in a con.- ventional relay. This provides thefeature. of, quick break which is a desideratum in alltelegraph relaydesign. As soon as the current in the relay windings reverses, thepressure between one pair oi contacts is released and thespider beginsto return to its normal position. so that.

the cont-acts which were open, will close together at twice the speedthey would in the conventional relay. Thus the arrangement provides fora quicker make and a quicker break than has. previously been obtained.

Consider now a relay employing this arrangement in which the fixedcontacts have been so. adjusted that they are both in contact with the.moving contacts simultaneously when the tongue is lying in a neutralposition. The instant,current is applied to the relay windings, one pairof contacts will be pressed into firmer contact. with each other whilethe other pair will immediately open. Thus it is possible with this.arrangement to adjust the relay to give a zero change-over time or evena make beforebreak facility without sacrificing-the anti-chatterfeatures provided by the use of resilient mountings for the contacts. I

In this embodiment, as so far described, the,

and the bush and the hub of thespider of some other shape, e. g. ofelliptical cross-section.

In practice, the spider is not necessarily formed as a straightcross-arm but may be so shaped that the faces of the two movingcontactsand, the axis of rotation of they spider lie inone plane.

It is not an essen at right angles to the direction of travel of thetongue.

If the damping provided by the internal friction of the material of theresilient bush is not considered adequate, additional frictional dampingcan be provided by arranging that the contact faces and the axis ofrotation of the spider lie in a plane not at right angles to thedirection of travel of the relay tongue. The rotational movement of thespider will then result in a sliding movement between the contact faceswhen they are pressed together. It has been found satisfactory toconstruct the relay with the plane containing the contact faces and theaxis of rotation of the spider making angles up to 45 with the directionof travel of the tongue, in fact even greater angles have been foundpracticable.

The description of the above embodiment makes the principle of theinvention clear and it is evident that the invention can be carried outin various different ways.

For example the spider could carry the fixed contacts and be resilientlymounted on the frame of the relay, the moving contacts being carried ona light cross-arm rigidly fixed to the relay tongue.

Another arrangement for carrying out the invention would be to mount thespider on the tongue of the relay employin a resilient bush, in such away, that the axis of rotation of the spider was parallel to the axis ofrotation of the relay armature. The two moving contacts would then be atdifferent distances from the axis of rotation of the armature so thecontact pressure on the two contacts would be different for equal signalcurrent strengths in the relay windings. This could readily becompensated for by making the arms of the spider of unequal length.

Yet another embodiment of the invention is shown in Fig. 2. In thisfigure there is shown a part of a relay tongue l2 which moves with thearmature under the influence of the signalling currents along the linesindicated by the arrows 13. The tongue carries at its free end aflexible extension in the form of a blade 14. A spider l 5 is firmlymounted on the free end of the blade l4 and carries two contact pieces[6, ll. These contact pieces co-operate with two adjustably mountedfixed contacts. It can be seen that this arrangement differs from thatshown in Fig. 1 only in that the resilient bush has been replaced by theflexible blade M. The quick make and quick break and make-before-breakfacilities described above are obtainable in just the same way as withthe embodiment described with reference to Fig. 1. However, the internalfriction in the blade I4 does not provide as much damping as theresilient bush of Fig. 1. In order to increase the damping, leaf springsl8 (having one end fixed to the rigid part 12 of the relay tongue andthe free end resting on the ends of the arms of the spider l5 as shownat 19) may be provided. When one of the contacts It or I! is pressedagainst its cooperating fixed contact the spider will be rotated againstthe resilience of the blade 14 and friction will occur where the leafsprings l8 are resting against the ends of the spider l5. By suitablyselecting the spring pressure and the fiexiblity of the blade I 4 adamping effect equivalent to that obtainable with the resilient bushconstruction can be obtained with the advantage that the properties ofthe springs will not vary with time and use as is liable to accur with aresilient bush made of organic material.

A still further embodiment of the invention is shown in Fig. 3. Thisrequires a somewhat different mechanical construction although thecontact 23 while the other moving contact is with-' drawn from the otherfixed contact 24.

The fixed contacts 23, 24 are themselves mounted on arms 25 attached toa rigid shaft 26, which is carried in bearings 21 and which liesparallel to the axis of the lever 20 when the latter is in-its neutralposition. It follows that any displacement of one of the fixed contactsmust be duplicated by an equivalent movement of the other fixed contact.Springs 28 are fitted which restrain the movement of the fixed contactsand at the same time act as conductors thereto. Insulating material mustbe introduced at some point to separate the two fixed contactselectrically, and in the figure the arms 25 are shown as being made ofan insulating material.

In this embodiment the resilience is supplied by the springs 28restraining the movement of the fixed contacts and if frictional dampingis necessary it can be provided by means of leaf springs (not shown)resting on the arms 25.

In this embodiment the lever 20 may constitute the armature of the relayor may be actuated by the rotation of the spindle 29 which is itselfunder the control of the relay armature.

Although several embodiments have been described indicating differentmechanical arrangements for carrying out this invention it is obviousthat anyone skilled in the art can apply the invention in other ways.

What is claimed is:

1. An electro-magnetic relay comprising a frame member, an armaturehaving an extension portion, a resilient bush of organic material firmlyattached to said portion, a rigid cross-piece provided with an aperturethrough which said resilient bush is passed, the inner surface of theaperture of said cross piece being firmly attached to the outer portionof said bush, said cross-piece being mounted at right angles to theplane in which said armature moves, a first pair of contacts attached tosaid cross-piece near the ends thereof, said contacts projecting inopposite sense along lines parallel to the line along which saidarmature moves, a second pair of contacts mounted on said member, saidlast named contacts positioned to co-operate with said first namedcontacts.

2. An electro-magnetic relay comprising an armature adapted to movebi-directionally in response to received signalling currents, a rigidmounting member, means for resiliently attaching said mounting member tosaid armature, a first pair of stationary, opposed contacts, a sec ondpair of opposed contacts, each attached to opposite sides of saidmounting member in a plane parallel to the direction of movement of saidarmature and spaced on opposite sides of the plane of movement of saidarmature, one of the contacts of said second pair adapted to cooperatewith one of the contacts of said first pair when said armature moves inone direction and the other of the contacts of said second pair adaptedto cooperate with the other of the contacts of said first pair when saidarmature moves in the other direction, said mounting member adaptedafter aamazsaa closures of corresponding ofthe contacts of said pairs tomove in one angular direction-and to;

move: in an opposite angular direction after closure of the othercorresponding contacts ofsaid pairs, said angular movement being in a 5means. 7

. 3.v An electro-magnetic relay as claimed in claim 2, wherein saidresilient means comprises an extension portion of said armature, saidportion in; the. form of a. thin, flexible and resilient blade, saidmounting member attached to, said portion at, the end of said bladedistant from the pointof attachmentv to said armature.

4: An. electro-magnetic. relay as claimed in claim 3, further comprisingdamping means. at-.

tached" to said armature and adapted to. exert pressure against saidmounting member.

VICTOR JOHN TERRY:

REFERENCES; CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name. Date 255,378 Connolly Mar. 21-,1882'- 57443351 Dixon Aug. 13,1895 781,416. Gregory Jan. 31, 1905-1279168 Smith Sept; 17, 1918' 2,082,493 Hartman June 1, 1931-"2,445,401, Langer July' 20, 1948;

Edwards et a1. Nov. 30,, 194d;v

